Portable tool for refacing drill pipe

ABSTRACT

Apparatus is provided for refacing pipe sections, the apparatus including a housing, a rotatable cutting head mounted on the housing by means of roller bearings and including thereon plural replaceable and adjustable cutting elements for cutting the desired surfaces of the pipe section, a feed screw for moving the cutting head longitudinally toward and away from the pipe section, and a threaded section operable to detachably secure the apparatus to the pipe section by rotation of said section. Rotation of the cutting head is provided by a ring gear which is operably connected to a source of power such as a small electric motor.

United States Patent 1 1 Pendleton [111 3,717,055 1 Feb. 20,- 1973PORTABLE TOOL FOR REFACING DRILL PIPE [76] Inventor: Earl M. Pendleton,5446 Apple Creek, Houston, Tex.

[22] Filed: Feb. 1, 1971 [21] Appl. No.: 111,356

[52] US. Cl. ..82/4 C [51] Int. Cl. ..B23b 3/22 [58] Field of Search..82/4 C [56] References Cited UNITED STATES PATENTS 3,124,024 3/1964Pittman ..82/4 C 3,540,328 11/1970 2,211,183 8/1940 2,159,287 5/1939Primary ExaminerLeonidas Vlachos Y Attorney-Arnold, White & Durkee, TomArnold, Robert A. White, Bill Durkee, Frank S. Vaden, Ill, Louis T.Pirkey and John F. Lynch [57] ABSTRACT cutting head longitudinallytoward and away from the pipe section, and a threaded section operableto detachably secure the apparatus to the pipe section by rotation ofsaid section. Rotation of the cutting head is provided by a ring gearwhich is operably connected to a source of power such as a smallelectric motor.

1 1 Claims, 9 Drawing Figures PAHL'NTED FEBZO {3T3 SHEET 10F 4 [a/'/ M.Pead/e f PATENTEU FEB2 0191a SHEET u 0F 4 A %M M4 MMA ATTORNEY) PORTABLETOOL FOR REFACING DRILL PIPE BACKGROUND OF THE INVENTION The inventionrelates to portable apparatus for refacing pipe, and has particularapplication to the refacing of drill pipe.

In the drilling of wells such as oil and gas wells, the driller utilizesmany sections (or joints) of threaded drill pipe. The individualsections are conveniently threaded together to form the drill stringthrough which it is customary to circulate a drilling fluid (such asdrilling mud) under pressure during the drilling process. Typically, thejoints of drill pipe have at one end a male or pin connection, and atthe other end a female or box connection. Box and pin connections areillustrated in these drawings, FIGS. 1 and 8, at 2 and 102,respectively.

It is important during the drilling process to maintain fluid-tightconnections between the various joints of drillpipe. For this reason,the connection between pin and box is quite important, and it iscritical that there be little or no fluid leakage.

It is apparent that to maintaining a fluid-tight seal between pin andbox connections, the threads of oneconnection must be perfectly alignedwith the threads of the other. This alignment is difficult to maintainduring drilling because of the frictional contact during 'makeup of thedrill string, and frictional wear of the connections during the drillingprocess under the extreme environmental conditions existing in theborehole. Since the joints of drill pipe are usually separated from thedrill string, stacked, "and used again, there is a special problem sinceadjacent connections will have been subjected to different amounts ofwear and therefore will not mate as well as connections which have beensubjected to identical wearing conditions.

More complete explanation of the problems of fluid seal in pin and boxconnections may be found in the application of Howard N. Keener, Ser.No. 723,843, filed Apr. 24, 1968, now U.S. Pat. No. 3,561,302.

Because of the necessity of maintaining a fluid-tight seal at the pinand box connections, it is often necessary to reface the inside bevel 5,end face 6, and outside bevel 7 of the box connection 2 (FIG. 1) if thejoint is to retain its useful life. Similarly, it is often necessary toreface the end face surface 105 and outside bevel 107 of pin member 102(FIG. 8).

Various types of machines have been used for such resurfacing, such asthat shown in the aforementioned U.S. Pat. No. 3,561,302. But all of theprior art apparatus known to the inventor suffers from one or more of anumber of very distinct disadvantages.

One primary disadvantage of prior art apparatus has been the heavy andbulky nature of the apparatus which has prevented field utilization ofthe apparatus. Consequently, it has often been necessary to transportpipe joints from remote locations to distant points at which the jointsmay be refaced.

Another distinct disadvantage of the prior art has been the necessityfor turning of the pipe being refaced, and/or fixed attachment of theapparatus to the pipe being refaced.

Still another disadvantage of the prior art has been the necessity toadjust or sharpen the cutting elements, thus often resulting in cuttingelements which are out of calibration.

Yet another disadvantage of the prior art has been the inability in muchprior art apparatus to simultaneously reface various of the surfaces.

Another disadvantage of certain prior art apparatus has been thenecessity for utilization of rather experienced operators and thedifficulty and expense in locating such operators.

It would be desirable if small portable apparatus could be providedwhich could be successfully used to reface the critical surfaces ofdrill pipe connections. Such apparatus is provided by the presentinvention.

It would further be desirable to provide apparatus of theabove-mentioned type which could be operated by the inexperiencedoperator. Such apparatus is provided by this invention.

It would be desirable to provide apparatus of the type mentioned above,which does not require turning of the pipe or affixing to the pipe. Thisinvention provides such apparatus, making it possible to stack aplurality of joints of pipe in racks and move the portable apparatus ofthis invention down such racks, refacing the connection surfaces of eachjoint seriatim.

It would also be desirable to provide apparatus which would make itprevent the use of out-of-calibration cutting elements. This inven ionprovides inexpensive cutting elements which, rather than being adjustedor field-sharpened upon dulling, may simply be discarded, and replacedwith a similar inexpensive element.

It would also be desirable to provide apparatus of the above mentionedtype, which would simultaneously reface the various surfaces of pin orbox connection. Such apparatus is provided by this invention, and theapparatus of the invention is capable of performing the necessaryoperations in a very short period of time.

The apparatus provided by the present invention may be operated by aninexperienced operator. It may be powered by a small electric motor. Itmay be utilized in the field, to thereby eliminate transportation ofpipe and thereby relieve the inventory problems which otherwise exist.

Other advantages of the present invention will be apparent from thediscussion which follows.

SUMMARY OF THE INVENTION The invention provides apparatus whichovercomes the disadvantages of the prior art as discussed above.

The present invention comprises apparatus which includes a housing,means for detachably securing the apparatus to a pin or box member, acutting head rotatable on said housing, cutting elements on the cuttinghead to reface the various desired surfaces of the pin or box member,and means for moving the rotatable cutting head into position adjacentthe pin or box member.

Means for detachably securing the apparatus to the pin or box memberdesirably comprise in accordance with the invention, a threaded adaptorportion which is rotatably engaged with the threads of pin or box memberby rotating a centrally disposed slide member by means of a handle. Themeans for moving the rotatable cutting head into position adjacent thepin or box member desirably comprises a feed screw which moves thecutting head longitudinally along the axis of the pipe member to beresurfaced independent of the adaptor portion which engages the threadsof the pipe. The feed screw is desirably turned by rotating a handlewhich protrudes from the housing.

The cutting elements in accordance with the invention are desirablysmall replaceable cutting elements which, after becoming dulled, maysimply be turned to expose a different face as the cutting surface, andmay thereafter be discarded with a new cutting element installed in itsplace.

The cutting head is rotated by means such as a ring gear which may bepowered by a small electric motor such as those generally available inthe field.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may bemore clearly understood, it will be explained in terms of particularlypreferred embodiments which represent the best mode known to applicantat the time of this application. Such embodiments are illustrated in theaccompanying drawings which form a part of this specification andwherein: p

FIG. 1 is an elevational view, in section, illustrating an embodiment ofthe invention suitable for refacing box members;

FIG. 2 is a view along the line 2-2 of FIG. 1;

FIG. 3 is a pictorial view of a cutting element useful in the apparatusof FIG. 1 suitable for refacing the face 6 of the box member 2;

FIG. 4 is a pictorial view of a cutting element useful in the apparatusof FIG. 1 suitable for refacing the outside bevel face 7 of the boxmember 2;

FIG. 5 is a pictorial view of a cutting element useful in the apparatusof FIG. 1, suitable for refacing the inside bevel face 5 of the boxmember 2;

FIG. 6 is a view taken along the line 6-6 of FIG. 1;

FIG. 7 is a view taken along the line 7--7 of FIG. 1;

FIG. 8 is a view similar to FIG. 1, but showing another embodiment ofthe invention which embodiment is suitable for refacing the surfaces ofa pin member; and,

FIG. 9 is a view taken along the line 9-9 of FIG. 8.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS In order to morecompletely describe the preferred embodiments of the invention,reference may first be had to the embodiment shown in FIGS. 1-7.

The portable refacing unit 10 of small size as seen in FIG. 1, comprisesgenerally housing means such as the outer housing 12, means forpositioning the apparatus in proper orientation against the surfaces tobe refaced such as the inner core portion 14, and a rotatable cuttinghead 16.

The central longitudinal axis a-a of the pipe joint to be refaced iscoincident to the longitudinal axis of the apparatus of this inventionwhen that apparatus is in its working position such as seen in FIG. 1,so the apparatus will be described in terms of the axis a-a as a centralreference axis.

The inner core portion 14 of the unit 10 extends substantiallysymmetrically about the axis a-a. This portion comprises an elongatebody portion or slide 18. The outer periphery of the slide 18 in thisembodiment forms a square, while the inner periphery forms a circle,leaving a longitudinally extending hollow portion 26 through the axialarea of the slide.

At one endof the slide 18 are means for removably affixing the slide tothe connection to be refaced, and at the other end of the slide aremeans for facilitating engagement of said means with the connection andmeans for moving the cutting head into operative cutting positionadjacent the surfaces to be refaced.

In this embodiment the means for removably affixing the slide to theconnection to be refaced comprises a tubular-shaped thread adaptor 20having an externally threaded portion which mates with the threads ofthe box member to be refaced.'The thread adaptor may be securely affixedto the slide 18 by any convenient means, as by the threaded engagementat 21 with an externally threaded segment of the slide at its extremityadjacent said adaptor, and by the nut 22 with washer 24 which threadsinto a threaded hole in the filled end of the slide 18. g

The threaded portion of thread adaptor 20 is tapered to a decreasingdiameter as the distance from the slide 18 increases, in order thatthere may be perfect mating relationship with the standard box fitting2.

Located at the end of the slide 18 opposite the thread adaptor 20, themeans for facilitating engagement of the thread adaptor into theconnection to be refaced, desirably comprise as in this embodiment asocket 28 into which fits an arm 30 connected to a handle 32. Turning ofthe handle 32 is thus effective to turn the slide 18 and thus the threadadaptor 20, thereby turning thread adaptor 20 into firm engagement withthe threads of the box member 2. Means are desirably included forholding the handle 32 out of the way of the operator during otheroperations, such means desirably including the pin 31 fitting into thesocket 28 on the side thereof opposite the handle 32.

' Means for moving the cutting head into operative cutting positiondesirably comprise as in this embodiment, a feed screw 34 located alongthe central longitudinal axis a-a. The feed screw 34 is turned by handle38 operating a wheel 36. Operation of the feed screw in moving thecutting head into operative cutting position will be described below.

The slide 18 contains therein a couple of longitudinally extending slots190, 19c disposed approximately apart, which slots are located near theend of the slide adjacent the thread adaptor 20.

The outer housing 12 of the unit 10 includes a body portion 40 having aprotruding housing portion 41 at the top thereof, and a tapered ring.48. The ring 48 has a couple of pins 54a, 54b affixed thereto, the pins54 being disposed approximately 180 from each other and protrudingthrough the slots 19 into the hollow central portion 26 of the slide 18.Each pin 54 is securely affixed to a circular block 56 which isthreadedly engaged by the feed screw 34, thereby to move the taperedring 48 (and hence the outer housing 12) upon turning of the feed screw.

The tapered ring 48 rests upon 'gibs 42a, 42b, 42c,

42d and is adjustable with respect thereto by means of v the apertures43 (two of which, 43a and 430 are illustrated in FIG. 1) and set screws46 extending therethrough.

Means for preventing movement of the housing during rotation of thecutting head are desirably included, and such means advantageouslyinclude a pin 52 which is disposed in one of a plurality of openings 50located around the periphery of the body 40 (See FIGS. 1 and 6). Thebody of the pin 52 is desirably grooved as indicated in FIG. 1, with aresilient member such as the spring 53 adapted for fitting into saidgrooves to lock the pin 52 in place.

A carrying arm 44 is desirably included on one side of the body 40 forconvenient pickup, carrying and holding of the unit 10. Such arm mightbe .of any convenient type.

The cutting head 16 is operably connected to the outer housing 12 androtates with respect thereto by means of the roller bearings 58, onepair of which are illustrated at 58a, 58b. The cutting head is thusoperable to move axially with the outer housing, but may rotate freelyaround the outer housing in a circle concentric with the axis a-a uponthe roller bearings 58. The cutting head 16 comprises in this embodimenta ring 60 fitted to turn on the bearings 58, and a flat circular facemember 62 disposed perpendicular to the axis a-a. The face plate member62 is adjustably connected to the ring 60 by means of the screws 64.

The face plate 62 has a large opening 63 concentric with the axis a-a ofsufficient size to accommodate the protrusion of the slide 18therethrough.

Replaceable individual cutting elements are positioned on the face 62 ofthe cutting head 16, desirably as illustrated in FIG. 2. Here is seenfor use in this embodiment for refacing the appropriate surfaces of thebox member 2, the ID (inside diameter) bevel cutter 84, the OD (outsidediameter) bevel cutter 76, and the face cutter 92. The individual toolsaccording to this embodiment of the invention are more fully illustratedin FIGS. 3, 4, and 5, and will be further described herebelow.

The replaceable individual cutting tools 76, 84, and 92 are desirablyspaced on the face plate 62 at about the same distance from the axisa-a, and at intervals of approximately 120 therearound. Each tool has acutting element which comprises a thin flat plate in the shape of anequilateral polygon. In these examples, the plate is in the form of asquare or equilateral triangle.

The OD bevel tool shown in FIG. 4 comprises a relatively large baseportion 78 which is adapted for attachment on the face 62 of the cuttinghead, and an upstanding portion 80 projecting therefrom in a direction(when the cutting tool is installed, as shown in FIG. 1) toward the ODbevel surface to be refaced. Longitudinal slots 77 are included in thebase 78 and the base is attached to the face 62 by means of screws 79fitting through these slots. The elongated slots permit adjustment ofthe tool 76 in the direction of such slots merely by positioning of thescrews 79 therein. The entire cutting tool-is thus adjustable to movethe cutting element radially toward or away from the desired surface,but the cutting element itself is nonadjustable. Rather, this element isturned or replaced when dulled. In this manner, improper adjustment ofthe cutting element itself is prevented while permitting simpleadjustment of the cutting tool.

The upstanding projection 80 presents a flat support surface 82 whichhas a threaded opening approximately centrally disposed therein. Thesupport surface 82 is adapted to support the replaceable cutting element74 which is readily affixed thereto by means of the screw 83 (FIG. 1)fitting into the threaded hole 81. The thin, flat square-shaped cuttingelement 74 presents four like surfaces, one of which is a cuttingsurface 75 which is effective to reface the OD bevel surface 7 of, box

member 2 as the cutting head rotates about the central axis a-a.

As will be readily understood, when the cutting surface of the element74 becomes dulled, the small element may be rotated to present anotherof the four like faces as the cutting face. After each such face hasbeen dulled, the element is quickly and readily replaced merely byremoving the screw 83 and the cutting element 74, and substituting a newelement.

The cutting tool 84 shown in FIG. 5 is substantially identical to thetool 76 except for the location on the base 86 of the tool, of theupstanding projection 88. The slots like the slots 77 provide foradjustment of the cutting tool along the line of the slots. Similarly,the surface 89 of upstanding projection 88 presents a support surfaceagainst which a removable cutting element 90 having four like faces, oneof which is a cutting face 91, is adapted to be positioned. Easyrealignment and removal and replacement of cutting elements is providedby the threaded hole 87 into which a suitable screw is adapted to befitted, in the same manner as described above in connection with thecutting tool 76.

The face cutting tool 92 comprises a generally solid block base portion96 which has a cutaway along a lateral axis thereof, the cutaway forminga couple of angular support surfaces 97 and 98 forming in cross sectiona V-shape along said lateral axis. A triangular shaped cutting element94 of sides 101, 102, and 103 fits into this V-shaped recess in such amanner that one of the sides 102 is supported by the surface 97 andanother of the sides 103 is supported by the surface 98. The top surfaceof the equilateral-triangle shaped cutting element, surface 101, is thusexposed as the cutting surface to act against the face 6 of box member2. When the surface 101 is dulled the element 94 may be turned toprovide a fresh cutting surface, and then when each of the surfaces 101,102, and 103 has become dulled, the element 94 is easily replaced by asimilar element.

The cutting member 94 is detachably retained in the base 96 by means ofan arm 99 and socket 100, retained by a screw 104. The base 96 of thecutting tool is retained on the cutting head by suitable means such asthe screws 93 in the recesses 95.

The cutting head 16 is driven by the ring gear 70 which may be poweredby any suitable means.

In this embodiment, the cutting head 16 is provided with a sprocketwheel 73 (See FIG. 6) which is driven by means of the ring gear 70turning on a core 71 mounted on a shaft 72. The shaft may be turned byany suitable means, but in this embodiment it is by means of a smallelectric motor 68. Desirably in accordance with this invention, a smallelectric motor (three-fourths horsepower, 1 10 volt) which is readilyavailable at sites in the FIGS. is useful for this purpose.

THE EMBODIMENT OF FIGURES 8-9 In FIGS. 8 and 9 is illustrated a furtherembodiment of the invention, this embodiment being useful to resurfacethe appropriate faces of a pin member rather than the box member refacedby the apparatus of the FIGS. 1-7 embodiment.

The pin member 106 presenting face surface and 0D bevel surface 107 isshown in position for operation in the refacing unit 1 10 of the FIGS.8-9 embodiment.

Like the unit 10 of the FIGS. 1-7 embodiment, the apparatus 110 may beconsidered to comprise generally an outer housing 112, an inner core114, and a rotatable cutting head 116. Also like the unit 10, the unit110 is disposed about a central longitudinal axis bb which is coincidentwith the central longitudinal axis of the pin member 106.

' The inner core portion 114 of the unit 110 extends substantiallysymmetrically about the bb axis. This portion comprises an elongate bodyportion or slide 118 which may be similar to the slide 18 of the FIGS.1-7 embodiment at the main body portion thereof opposite the pin member106, but toward the end adjacent the pin member 106, the slide 118 isradially outwardly flared to terminate in means for attaching the slideto the connection to be refaced, such as the internally threaded threadadaptor portion 120. The portion 120 is adapted to threadedly engage andmate with the threads of the pin member 106.

The main body portion of the slide 118 is equipped with a couple ofslots 119a, 119b, extending for a short distance along the axis bb. Asin the FIGS. 1-7 embodiment, the slide 118 defines a centrallongitudinal hollow portion 126 extending through the main body thereof.

At the end of the slide 118 opposite the pin member 106, is means forfacilitating engagement of the thread adaptor with the connection, andmeans for moving the cutting head 116 into operative cutting positionadjacent the surfaces to be refaced. In this embodiment of theinvention, such means for engaging the thread adaptor 120 desirablycomprise a socket 128 into which fits an arm 130 which may beconveniently turned by a handle 132. Turning of the handle 132 is thusoperative to turn the slide 118 and the thread adaptor 120, sufficientturning in this manner thereby enabling firm threaded engagement of thethread adaptor with the pin member 106.

Means for moving the cutting head 116 into operative engagement with thepin member 106, desirably comprise a feed screw 134, located along theaxis bb. The feed screw 34 is desirably turned by a handle 138 operatinga wheel 136 rotating with the feed screw 134.

The outer housing 112 of the unit 110, includes a body portion 140having at the top thereof in the FIG. 8 orientation, a protrudinghousing portion 141, and an annular inner portion 148 which terminatesat the end thereof nearest the pin member 106, in a longitudinallyextending tapered ring 148.

The tapered ring 148 rides on gibs 142 which separate the ring 148 fromthe exterior surface of the thread adaptor 120.

The inner portion 147 which is integral in this embodiment with the ring148, being connected thereto by a flared portion 145, and is equippedwith a couple of pins 154a, 154b, which project radially inwardlythrough the slots 1190, 11%, respectively, in the slide 118, into thehollow central portion 126 of the slide 1 18. Each pin 154 is securelyafi'lxed to a circular block 156 which is threadedly engaged by the feedscrew 134 (in this connection it will generally be desirable to use aleft-handed feed screw 134 to prevent disengagement upon turning withthe block 156) thereby to move the inner portion 147 and hence the outerhousing 112 upon turning of the feed screw 134.

Means for preventing movement of the housing during rotation of thecutting head are desirably provided, and such means desirably include apin 152 which is disposed in one of a plurality of holes located aroundthe periphery of the body 140, the pin 152 being grooved to cooperatewith a spring 153.

As in the FIGS. 1-7 embodiment, a carrying arm 144 is desirably includedon one side of the body 140 for convenient pickup, carrying and holdingof the unit 1 10. Such arm might be of any convenient type, such as thatillustrated in FIG. 8 and shown in the previously described embodimentin FIGS. 1 and 6.

The cutting head 116 is operably connected to the outer housing 112 androtates with respect thereto, by means of the roller bearings 158a,158b. The cutting head is thus operable to move axially with the housing112 but is free for rotation therearound (around the axis bb) while thehousing 112 is stationary.

The cutting head 116 in this embodiment, comprises a ring 160 fitted toturn on the bearings 158, and a flat circular face member 162 disposedperpendicular to the axis bb. The face plate member 162 has a largeopening 163 centrally disposed therein of a size sufficient toaccommodate the threaded portion of the pin member 106 therein.

As in the FIGS. 1-7 embodiment, replaceable cutting tools are providedon the face 162 of cutting head 116, as illustrated in FIGS. 8 and 9.However, since only two cutting tools are required for the pin member106, these being an OD bevel cutting tool 176 and a-face cutting tool192. l

The cutting tools 176 and 192 are desirably substantially equidistantlyspaced around the periphery of the face 162, in this embodimenttherefore being approximately 180 apart.

The OD bevel tool 176 is like the OD bevel tool 74 shown in the FIGS.1-7 embodiment and bestillustrated in FIG. 4. The tool 176 comprises abase portion 178 and an upstanding portion 180, the base beingadjustably affixed to the face 162 by means of screws 179 which fit inelongate slots 177. A cutting element 174 presents a cutting surface 175with three similar surfaces which are useful after the surface 175 hasbecome dulled in use. v

Likewise, the cutting tool 192 is similar to the cutting tool 92 of theFIGS. 1-7 embodiment.

As previously stated, the individual cutting tools are readilyreplaceable in the field by the inexperienced worker, and this is one ofthe desirable attributes of the present invention.

Similar to the FIGS. 1-7 embodiment, the cutting head 1 16 is turned bya ring gear 170 turning on a shaft 172, which may be powered by a smallelectric motor of the type readily available in the field, as mentionedheretofore.

Means are desirably included to ensure that the faces 105 and 107 arenot cut too deeply. Such means desirably comprise in this embodiment,the inner face of the nut 167, which serves as a stop means uponengagement with the adjacent surface of the block 156. Once there iscontact between the surface 165 and the block 156, the pin member canmove no closer to the cutting tools and thus it is assured that thesurfaces 105, 107 will not be damaged by excessive cutting.

From the above description, it is seen that apparatus is provided bythis invention which does not require turning of the pipe joint toresurface the various faces of pin and box members. Neither does theapparatus of the invention require affixation of the apparatus to thepipe. Rather, the apparatus is desirably detachably connected to thepipe as described above.

Further, it is seen that the invention provides a lightweight, portableapparatus which may be powered by a small electric motor of the typereadily available in the field.

It is further seen that apparatus is provided whereby pipe may bestacked in racks, and the apparatus moved down the rack to reface eachmember seriatim.

The invention provides inexpensive replaceable cutting tools which canbe rotated to expose a new face, and then thrown away when dulled. Sincethe cutting tools are not adjusted or field-sharpened, there is no risk,as there is in prior art tools, of cutting the surfaces out ofcalibration or alignment.

The invention provides for the first time, a small practical refacingtool which can be used in the fieldthereby avoiding costly downtimeespecially where offshore applications are concemed-by inexperiencedpersonnel, having the advantages mentioned above, and being economical,providing'sirnultaneous cutting in a very short time (3 minutes isusually sufficient for the embodiments disclosed) of the various facesto be resurfaced, in a manner such that the pipe is refaced true to thethreaded seat and thread axis, to assure no loss of pressure in d'rillfluids circulated through the pipe after the pipe has been returned toservice.

Although the invention has been described in terms of particularlypreferred embodiments which represent the best mode of the inventionknown to the applicant at the time of this application, it will beapparent to those of skill in the art that various modifications mightbe made in the structures herein described, without departing from thescope of the invention which is defined in the appended claims.

What is claimed is:

l. Lightweight, portable apparatus suitable for field use to refacedesired surfaces of a pipe member comprising:

a housing adapted to receive said pipe member in a manner such that thelongitudinal axis of said pipe member is coincident with thelongitudinal axis of said housing;

a rotatable cutting head mounted on said housing, in a manner such thatsaid cutting head is movable longitudinally along said axes with saidhousing but is rotatable about said axes independent of said housing;

at least one cutting tool mounted on said cutting head in a manner suchthat the desired surfaces of said pipe member may be refaced as saidcutting tool rotates about said axes on said cutting head;

means including a threaded section adapted to mate with the threads ofsaid pipe member, said section being carried on a slide member extendingalong said axes and having at least two longitudinally extending slotstherein, and a hollow central portion along said axes,

for detachably securing said apparatus to said pipe member;

a feed screw disposed in said hollow central portion and connected withpins extending through said slots, rotating ofsaid feed screw beingeffective to move said housing and said cutting head axially but suchrotation not causing movement of said slide and threaded section; and,

means on said housing for rotating said cutting head.

2. Apparatus in accordance with claim 1, said slide member beingconnected to a handle at the end thereof opposite said pipe member, andsaid handle being operable upon turning to rotate said engagement withsaid pipe member.

3. Apparatus in accordance with claim 1, wherein said cutting toolincludes a cutting element which has plural surfaces adapted for cuttingthe desired surface, and wherein said element is detachably mounted onsaid cutting head in a manner such that the element may be readily andeasily turned to present a different face as a cutting surface after onesuch surface becomes dulled in operation.

4. Apparatus in accordance with claim 3, wherein said cutting element isa thin flat member in the shape of an equilateral polygon, saidcuttingelement being readily detachably mounted against a supportsurface on said cutting tool.

5. Apparatus in accordance with claim 4, wherein said cutting toolcomprises a base and an upstanding portion, said upstanding portionpresenting said support surface, and said base being secured to saidcutting head by fastening means therein, said fastening means extendingthrough elongate slots in said base in a manner such that said cuttingtool may be readily adjusted to move said cutting surface toward or awayfrom said pipe member.

6. Apparatus in accordance with claim 1, wherein said means for rotatingsaid cutting head comprises a ring gear, said housing including teethfor meshing with said ring gear.

7. Lightweight, portable apparatus suitable for field use to refacedesired surfaces of a pipe member comprising:

a housing adapted to receive said pipe member in a manner such that thelongitudinal axis of said pipe member is coincident with thelongitudinal axis of said housing, said housing including rollerbearings mounted concentrically around said axes; rotatable cutting headmounted on said roller bearings such that said cutting head is movablelongitudinally along said axes with said housing but is rotatable aboutsaid axes independent of said housing; at least one cutting tool mountedon said cutting head in a manner such that the desired surfaces of saidpipe member may be refaced as said cutting tool rotates about said axeson said cutting head; means including a threaded tubular section adaptedto mate with the threads of said pipe member, said section being carriedon a slide member extending along said axes and having at least twolongitudinally extending slots therein, and a hollow central portionalong said axes, and

a handle at the end of said slide member opposite said threaded section,said handle being operable upon turning to rotate said housing and tomove said threaded section into mating threaded engagement with saidpipe member; for detachably securing said apparatus to said pipe member;

a feed screw disposed in said hollow central portion and connected withpins extending through said slots, rotating of said feed screw beingeffective to move said housing and said cutting head axially but suchrotation not causing movement of said slide and threaded section; and,

means on said housing for rotating said cutting head.

8. Apparatus in accordance with claim 7, wherein said cutting toolincludes a cutting element which has plural surfaces adapted for cuttingthe desired surface, and wherein said element. is detachably mounted onsaid cutting head in a manner such that the element may be'readily andeasily turned to present a different face as a cutting surface after onesuch surface becomes dulled in operation.

9. Apparatus in accordance with claim 8, wherein said cutting element isa thin flat member in the shape of an equilateral polygon, said cuttingelement being readily detachably mounted against a support surface onsaid cutting tool.

10. Apparatus in accordance with claim 9, wherein said cutting toolcomprises a base and an upstanding portion, said upstanding portionpresenting said support surface, and said base being secured to saidcutting head by fastening means therein, said fastening means extendingthrough elongate slots in said base in a manner such that said cuttingtool may be readily adjusted to move said cutting surface toward or awayfrom said pipe member.

11. Apparatus in accordance with claim 7, wherein said means forrotating said cutting head comprises a ring gear, said housing includingteeth for meshing with said ring gear.

' i i 1 i i

1. Lightweight, portable apparatus suitable for field use to refacedesired surfaces of a pipe member comprising: a housing adapted toreceive said pipe member in a manner such that the longitudinal axis ofsaid pipe member is coincident with the longitudinal axis of saidhousing; a rotatable cutting head mounted on said housing, in a mannersuch that said cutting head is movable longitudinally along said axeswith said housing but is rotatable about said axes independent of saidhousing; at least one cutting tool mounted on said cutting head in amanner such that the desired surfaces of said pipe member may be refacedas said cutting tool rotates about said axes on said cutting head; meansincluding a threaded section adapted to mate with the threads of saidpipe member, said section being carried on a slide member extendingalong said axes and having at least two longitudinally extending slotstherein, and a hollow central portion along said axes, for detachablysecuring said apparatus to said pipe member; a feed screw disposed insaid hollow central portion and connected with pins extending throughsaid slots, rotating of said feed screw being effective to move saidhousing and said cutting head axially but such rotation not causingmovement of said slide and threaded section; and, means on said housingfor rotating said cutting head.
 1. Lightweight, portable apparatussuitable for field use to reface desired surfaces of a pipe membercomprising: a housing adapted to receive said pipe member in a mannersuch that the longitudinal axis of said pipe member is coincident withthe longitudinal axis of said housing; a rotatable cutting head mountedon said housing, in a manner such that said cutting head is movablelongitudinally along said axes with said housing but is rotatable aboutsaid axes independent of said housing; at least one cutting tool mountedon said cutting head in a manner such that the desired surfaces of saidpipe member may be refaced as said cutting tool rotates about said axeson said cutting head; means including a threaded section adapted to matewith the threads of said pipe member, said section being carried on aslide member extending along said axes and having at least twolongitudinally extending slots therein, and a hollow central portionalong said axes, for detachably securing said apparatus to said pipemember; a feed screw disposed in said hollow central portion andconnected with pins extending through said slots, rotating of said feedscrew being effective to move said housing and said cutting head axiallybut such rotation not causing movement of said slide and threadedsection; and, means on said housing for rotating said cutting head. 2.Apparatus in accordance with claim 1, said slide member being connectedto a handle at the end thereof opposite said pipe member, and saidhandle being operable upon turning to rotate said engagement with saidpipe member.
 3. Apparatus in accordance with claim 1, wherein saidcutting tool includes a cutting element which has plural surfacesadapted for cutting the desired surface, and wherein said element isdetachably mounted on said cutting head in a manner such that theelement may be readily and easily turned to present a different face asa cutting surface after one such surface becomes dulled in operation. 4.Apparatus in accordance with claim 3, wherein said cutting element is athin flat member in the shape of an equilateral polygon, said cuttingelement being readily detachably mounted against a support surface onsaid cutting tool.
 5. Apparatus in accordance with claim 4, wherein saidcutting tool comprises a base and an upstanding portion, said upstandingportion presenting said support surface, and said base being secured tosaid cutting head by fastening means therein, said fastening meansextending through elongate slots in said base in a manner such that saidcutting tool may be readily adjusted to move said cutting surface towardor away from said pipe member.
 6. Apparatus in accordance with claim 1,wherein said means for rotating said cutting head comprises a ring gear,said housing including teeth for meshing with said ring gear. 7.Lightweight, portable apparatus suitable for field use to reface desiredsurfaces of a pipe member comprising: a housing adapted to receive saidpipe member in a manner such that the longitudinal axis of said pipemember is coincident with the longitudinal axis of said housing, saidhousing including roller bearings mounted concentrically around saidaxes; a rotatable cutting head mounted on said roller bearings such thatsaid cutting head is movable longitudinally along said axes with saidhousing but is rotatable about said axes independent of said housing; atleast one cutting tool mounted on said cutting head in a manner suchthat the desired surfaces of said pipe member may be refaced as saidcutting tool rotates about said axes on said cutting head; meansincluding a threaded tubular section adapted to mate with the threads ofsaid pipe member, said section being carried on a slide member extendingalong said axes and having at least two longitudinally extending slotstherein, and a hollow central portion along said axes, and a handle atthe end of said slide member opposite said threaded section, said handlebeing operable upon turning to rotate said housing and to move saidthreaded section into mating threaded engagement with said pipe member;for detachably securing said apparatus to said pipe member; a feed screwdisposed in said hollow central portion and connected with pinsextending through said slots, rotating of said feed screw beingeffective to move said housing and said cutting head axially but suchrotation not causing movement of said slide and threaded section; and,means on said housing for rotating said cutting head.
 8. Apparatus inaccordance with claim 7, wherein said cutting tool includes a cuttingelement which has plural surfaces adapted for cutting the desiredsurface, and wherein said element is detachably mounted on said cuttinghead in a manner such that the element may be readily and easily turnedto present a different face as a cutting surface after one such surfacebecomes dulled in operation.
 9. Apparatus in accordance with claim 8,wherein said cutting element is a thin flat member in the shape of anequilateral polygon, said cutting element being readily detachablymounted against a support surface on said cutting tool.
 10. Apparatus inaccordance with claim 9, wherein said cutting tool comprises a base andan upstanding portion, said upstanding portion presenting said supportsurface, and said base being secured to said cutting head by fasteningmeans therein, said fastening means extending through elongate slots insaid base in a manner such that said cutting tool may be readilyadjusted to move said cutting surface toward or away from said pipemember.